How Does It Work - Blinding

• Given

  • Message m
  • Bank private key d,N
  • Bank public key e,N
  • Random number r

• We want to get a signed message: md

• Fun Math Stuff tells us that:

  • aed = a (mod N)
  • (rm)d = (rd)(md) (mod N)

• Alice blinds the message

  • (re)(m) = M (mod N)

• Bank does not know the original message m